A low molecular weight (8500 plus or minus 1500 Daltons) material, which is common to at least three type A strains of Clostridium perfringens, was separated from the "type-specific" polysaccharides by (NH4)2SO4 fractionation. Further purification was accomplished by enzyme treatment with RNase and papain. Residual "type-specific" polysaccharide and other charged species were removed by chromatography on DEAE A25; the "common antigen" appearing in the water wash. Chemical analysis indicated that the major carbohydrate constituent was N-Acetylglucosamine with traces of N-acetylgalactosamine, glucose and galactose. The DEAE A25 fraction did not react with homologous antiserum in double diffusion in Gel; but a strong reaction for the "common antigen" was observed.